Curved assembly line and/or conveyor belt

ABSTRACT

The invention relates to a curved assembly line and/or conveyor belt, especially for assembling and transporting motor vehicles or motor vehicle parts during production, said line or belt being formed by articulated carrier elements that positively engage in each other and respectively comprise an upper platform and a lower carrier frame and have convex and concave front surfaces with identical curvature radii. The aim of the invention is to enable an essentially tangential orientation of the platforms in the curved region with a simple course of displacement and low control costs. To this end, respective carrier elements ( 2 ) with concave ( 9 ) and convex front surfaces ( 6,7 ) on both sides alternate in the longitudinal direction of the assembly line and/or conveyor belt ( 1 ), and the respective carrier elements ( 2 ) with concave front surfaces ( 9 ) on both sides are embodied as short intermediate elements ( 8 ) which are located between the carrier elements ( 2 ) receiving the load and have convex front surfaces ( 6,7 ) on both sides.

The invention relates to a curved assembly line and/or conveyor belt, inparticular for the assembly and transport of motor vehicles or motorvehicle parts in production, which is formed by carrying elements whichare mounted in an articulated manner with respect to one another andengage positively one into the other and which have in each case anupper platform and a lower carrying frame and the end faces of which areconvexly and concavely curved in the form of an arc of a circle withapproximately identical radii of curvature, so that in each case aconvex and a concave recess of two adjacent carrying elements form,bearing positively one against the other, a continuous conveyor belttransition both in curved sections and on a straight line.

Assembly lines and/or conveyor belts serve, in automobile production,for reception of automobile parts, in particular bodies, in theexecution of assembly work and for other production and transport work.The automobile workers working on the automobile parts normally movealong with the slowly moving conveyor belt and can move freely on theplatform. The individual carrying elements of these assembly linesand/or conveyor belts have wheels or are carried on roller strips. Thedrive takes place mostly via driven roller batteries which transmit thedrive force to the carrying elements by frictional connection. The drivestations are usually arranged at the commencement of a straightconveying section.

Force transmission from carrying element to carrying element takes placeon straight conveying sections by means of pushing forces, and at theends of the conveying sections the carrying elements are braked via abraking station, in order to avoid gaps in the composite pushingstructure. Downstream of the braking station, the draw-off stations areusually arranged, which execute a “staggered drawing” of the carryingelements, in order to allow a cross transfer or a vertical transfer, forexample by means of a lifter. The rotational movement of the carryingelements usually describes a rectangle. However, other layouts arepossible.

The known assembly lines and/or conveyor belts of the type describedhave various disadvantages. If, for example, the direction of travel ofthe carrying elements is maintained after the cross transfer, then a180-degree rotation of the carrying elements is required. The cornertransfer necessary for this purpose is a blocked region; that is to say,it is not available for assembly work on the automobile and,furthermore, without a high outlay in terms of protection, constitutes ahigh risk potential. Corner transfer itself requires a complex sequenceof movement with high outlay in control terms, and also the power supplyof the platforms presents problems on account of the corner transfer.

Curved carrying elements are also known (DE-A-198 58 989), which,rotating in a closed circuit, form the assembly line and/or conveyorbelt, a semicircular curve with a normally constant curve radiusfollowing a straight conveying section on both sides. In order to avoidgaps and rifts between the adjacent carrying elements, particularly inthe curved sections, the carrying elements have in each case a concaveand a convex end face, in each case with an identical radius and centerpoint. The carrying elements can also be operated in an open compositestructure. There, too, the drive takes place via stationary rollerbatteries or via co-moving individual drives.

These curved carrying elements have the disadvantage that, because ofthe polygon effect of the elongated carrying elements, wide covers whichclose the rifts between the adjacent carrying elements are required inthe curved sections, with the result that the useful area available onthe platform in the curve is reduced considerably.

The result of this is that, below a particular curve radius, sometimesthe standing area for, for example, an automobile or a body becomes toonarrow. In curves with a low ratio of curve radius to length of carryingelements, a considerable polygon effect arises, which, particularly in aclosed circuit, leads to a permanent change in the length of rotation.These length changes have to be compensated by means of structuralmeasures; a tangential orientation of the platforms in the arc is notpossible in this prior art.

The object of the present invention is to provide a curved assembly lineand/or conveyor belt of the generic type, which, along with a simplemovement sequence and low outlay in control terms, makes it possible, byvirtue of its design, to have an essentially tangential orientation ofthe platforms in the arc region, so that, on account of narrowstationary covers of the assembly line and/or conveyor belt, a largeruseful area is available on the platform in the curved region.

To achieve the object, it is proposed, according to the invention, toalternate with one another in the longitudinal direction of the assemblyline and/or conveyor belt in each case carrying elements with end facesconcave on both sides and with end faces convex on both sides, and ineach case to design the carrying elements with end faces concave on bothsides as short intermediate elements between the load-receiving carryingelements with end faces convex on both sides.

In order to avoid gaps between the platforms and the disadvantagesdescribed with regard to the prior art, the carrying elements areconfigured and assembled into the assembly line and/or conveyor belt insuch a way that, in each case alternately, one carrying element has twoconvex end faces and the second adjacent carrying element, theintermediate element, as it is referred to, has two concave end faces.

By virtue of this proposal, the polygon effect during the deflection ofthe platforms in the curved sections is markedly reduced, but theorientation of the platforms with respect to the direction of travel ismaintained, so that the corner transfer required hitherto may bedispensed with.

All the carrying elements together with their attached platforms aremechanically connected fixedly to one another, that is to say there isno risk that, for example due to a malfunction of the control, a gapbetween two adjacent platforms occurs, which could lead to persons beingput at risk.

Owing to the use of the short intermediate elements which allow anessentially tangential orientation of the carrying elements togetherwith their platforms in the arc region of the conveying path, it ispossible for assembly work to be carried out even in the arc because ofthe high space utilization. Barriers or other safety measures extendingbeyond the stationary covers in the curves are not required.

The kinematics according to the invention also make it possible toemploy long carrying elements for the reception of large payloads andlong articles, for example long automobiles. The modular construction ofthe conveyor belt and assembly line according to the invention makes itpossible to change the stroke interval simply by exchanging theintermediate elements, without the carrying element together with themain platform itself having to be changed. The plant can be operated,overall, with a low polygon effect.

Preferably, according to the invention, a multiplicity of carryingelements are joined together via connecting members into a closed oropen composite platform structure. A closed composite platform structureleads to

a carousel-like rotation of the carrying elements on a path closed onitself.

In a preferred refinement of the invention, the connecting members ofthe carrying elements are coupling rods, in each case two adjacentcarrying elements separated by a common intermediate piece and havingconvex end faces being connected to one another in an articulated mannerby means of a common coupling rod, in such a way that the twoarticulation points of each coupling rod lie in each case on the radiuscenter points of those end faces of the carrying elements which arecurved concavely in the form of an arc of a circle.

The selected kinematics and the configuration of the carrying elementsensure that the end faces of the carrying elements roll against oneanother, without giving rise to gaps between the platforms. The carryingelements move around the curve in a tangential orientation with respectto the curve curvature. Owing to the mechanical connection of thecarrying elements, secure connection takes place even in the curvedsections, without constraints in the system arising.

According to the invention, roller guides or sliding guides, which allowa friction-free or low-friction displacement of the adjacent carryingelements with respect to one another, are provided on the end face inthose regions of the carrying elements which face one another.

The drive of the carrying elements of the invention may take place in away known per se by means of a plurality of friction-wheel stationsdistributed along the travel of the carrying elements. According toanother proposal of the invention, however, it is also possible that thedrive of the assembly line and/or conveyor belt takes place viaindividual drives which are assigned to at least every nth carryingelement and which are arranged, co-moving, on the corresponding carryingelement.

In the case of electric drives, according to another feature of theinvention, the energy and/or data supply of the carrying elements takesplace permanently via contact lines which are laid next to or below thecarrying elements along the travel.

Within the scope of the invention, it is also conceivable that theenergy and/or data supply takes place permanently or inductively insections. As a result, disturbing lines are avoided and transitions aresimplified.

According to a further feature of the invention, there is provision forthe guidance of at least every second carrying element to take place viaguide rails laid on the ground.

As is known in other undercarriages, in order to achieve lateral tiltstability, according to the invention, the distance between two guiderails laid as a double track with a spacing between them is reduced inthe curved region. As a result, constraints on the undercarriages due tothermal effects and due to the polygon effect during passage throughcurves are avoided, particularly when the inner of the two guide railsis designed both as a carrying and as a guide rail.

In most instances, it is expedient if the carrying elements rotating ina closed composite platform structure are guided on an oval(stadium-shaped) path of rotation. In such an instance, the complicatedcorner transfers and the cross connection sections which are employed inthe prior art and cannot be used for assembly purposes are dispensedwith. Instead, because of the advantageous kinematics of the carryingelements according to the invention, assembly is possible even in thecurved regions, and the plant capacity can be fully utilized owing tothe larger available useful area on the platform.

According to a further refinement of the invention, the lateral guidanceof the carrying elements takes place at outer and/or inner carryingrails. In this case, a specific guidance of the intermediate elements isnot required, because, due to the coupling to the adjacent carryingelements guided on the guide rails, the intermediate elements are takenup in a freely guided manner. Spacing takes place via the coupling rods.

As a refinement, active or passive lifting devices, which serve as anassembly aid, may be installed in at least individual carrying elements.These lifting devices can, when controlled, for example, by slottedlink, make it possible separately to raise or lower each individualwheel of the four wheels of an automobile. Also, other expedientfittings, such as, for example, suction-extraction devices, may also becarried on the platforms of the carrying elements.

So that even a change in level of the plane of rotation can be executedby means of the carrying elements according to the invention, accordingto another feature of the invention, vertical arcs are provided in thecarrying and/or guide rails, and the carrying elements are additionallyconnected to one another via horizontal joints.

Finally, there is provision for the carrying elements designed as anintermediate element to be configured so as to be easily removable forinspection and/or maintenance purposes.

According to a particularly beneficial feature of the invention,vertical load transmission takes place via co-moving steel rollers onthe underside of the carrying elements, preferably all the carryingrollers being mounted rotatably about their vertical axes. In the caseof a low rolling resistance of the metallic carrying rollers, alow-slung type of construction requiring no pit is obtained. Theplatform itself is advantageously formed by a plywood layer

which can be walked on by persons and, for vehicle removal, can bedriven on.

The invention has a multiplicity of advantages which are collated asfollows:

The invention is simple in construction and has high functionalreliability. Owing to the tangential orientation of the carryingelements in the curves, narrow covers can be implemented, which allow alarge interspacing even in the arc. This makes it easier to installlifting devices controlled by slotted link, active lifting tables,suction-extraction systems, etc. The carrying elements together with theplatforms can be operated in a closed or open composite structure. Thedrive takes place via stationary roller batteries or via co-movingindividual drives. No intermediate covers are required between theplatforms of the carrying elements. The orientation of the platformswith respect to the direction of travel is always maintained, and thereis no need for any corner transfer. The movement sequence is simple andrequires only a low outlay in control terms. Since all the platforms aremechanically connected fixedly to one another, there is no risk that,for example due to a malfunction of the control, a gap between twoadjacent platforms occurs, which could lead to persons being put atrisk. The uniform drives make a closed contact line for energy and datatransmission possible.

The invention makes it possible for assembly work to be carried out evenin the arc of the curved region, thus resulting in a high spaceutilization, because there is no need for any barriers or other safetymeasures which extend beyond stationary (flat) covers which, even in thearc, leave open large fractions of the useful area of the mainplatforms.

By virtue of the measures of the invention, the carrying elements andconsequently the main platforms can be made larger, and

make it possible to receive large payloads, for example longautomobiles, and further fittings, such as suction-extraction systems,etc.

The stroke interval of the assembly line and/or conveyor belt can bevaried by adapting the intermediate element, without the main platformhaving to be changed. Finally, the use of metallic carrying rollers withlow rolling resistances allows a low-slung type of construction, so thatno pit is required. The cover of the intermediate elements can easily beremoved for maintenance and repair purposes.

An exemplary embodiment of the invention is illustrated in the drawingand is described below. In the drawing:

FIG. 1 shows the assembly line and/or conveyor belt according to theinvention for the assembly and/or transport of a motor vehicle,

FIG. 2 shows an assembly line and/or conveyor belt according to theprior art,

FIG. 3 shows an enlarged illustration of the curved region of anassembly line and/or conveyor belt according to the invention,

FIG. 4 shows the frame of a carrying element according to the invention,and

FIG. 5 shows a carrying element according to the invention designed asan intermediate element.

The drawing FIG. 2 illustrates, roughly diagrammatically, an assemblyline and/or conveyor belt 1, such as is known and described in the priorart. The assembly line and/or conveyor belt is used in the automobileindustry for the assembly and transport of motor vehicles and consistsof carrying elements 2 which are mounted in an articulated manner withrespect to one another and engage positively one into the other andwhich are guided on an endless conveying section. The individualcarrying elements 2 are in each case designed convexly on their endfaces 4 leading in the conveying direction 3 and concavely on theiropposite end faces 5, so that, when the carrying elements 2 rotate, theleading end faces 4 of the one carrying element 2 engage positively inthe trailing end faces 5 of the carrying element 2 adjacent to theconveying direction 3, in such a way that a continuous transitionbetween the adjacent carrying elements 2 is afforded both in the curvedregion and on the straight conveying section. As can be seen in FIG. 2,the carrying elements 2 move around the curve in a polygonalprogression, the carrying elements 2 coupled to one another moving, inregions, laterally out of the curved profile which resembles an arc of acircle.

If it is considered that the carrying elements 2, slowly moved along asmuch as possible at the same level as the ground, are to be walked uponsafely by the workers and, if appropriate, the finished vehicles arealso to be driven down off them from the platform, it becomes clear thatmeasures must be taken in the curved region in order to prevent bothlaterally and on the end faces of the carrying elements gaps whichthreaten to put at risk workers working there. For this reason, thoseside regions of the carrying elements 2 which are formed and resemble apolygonal progression are spanned in the curved region by covers A1 andA2 which cover the gaps occurring due to the polygonal progression. Themore pronounced is the polygonal effect during deflection around thecurve or the more narrowly the curve is deflected, the more widely thecovers A1 and A2 required must span the carrying elements 2. The resultof this is that the work platform remaining between the outer A2 and theinner A1 covers is markedly narrower in the curved region than in theregion where the parking elements run in a straight line. In an extremecase,

the platform for a vehicle or a body placed on it may be too narrow, sothat assembly in the curved region becomes impossible.

The drawing FIG. 1 illustrates, roughly diagrammatically, how theproblem is solved by means of the invention. According to the invention,the carrying elements 2 of the assembly line and/or conveyor belt 1 aredesigned convexly on both end faces 6, that is to say the end facesdirected both in the conveying direction and opposite to the conveyingdirection, the same curvatures corresponding in each case to the segmentof a circle. The carrying element adjacent in each case, as anintermediate element 8, is designed to be shorter than the carryingelement 2 and has on its two end faces concave recesses 9 which face theend faces 6 of the carrying elements 2 and which, like the end faces ofthe carrying elements 2, are formed in each case from circle segmentshaving identical radii.

As can be seen in the enlarged illustration of a curved profile of anassembly line and/or conveyor belt according to the invention in FIG. 3,the intermediate elements 8 have fastened to them central coupling rods10 which extend symmetrically on both sides of the intermediate elements8, to which they are fastened, into the region of the carrying elements2, where the coupling rods 10 are articulated at 11. The articulationpoint 11 of the coupling rods 10 is arranged at the radius center pointboth of the end faces 6 and 7 of the carrying elements 2 and of theconvex or concave end faces 6 and 9 of the intermediate elements 8, sothat the end faces, for example 6 and 9, of a carrying element 2 and ofan intermediate element 8 roll one on the other, positively guided bythe coupling rod 10, when the carrying elements 2 and intermediatepieces 8 move in the curved region. The coupling rods 10, which areprovided on each intermediate element 8 and are connected in each caseto the two adjacent carrying elements 2, have the effect that, in anassembly line and/or conveyor belt of the invention, a substantiallyfiner polygonal division is brought about, and, above all, that

the carrying elements 2 always move tangentially with respect to thecurved path 15 of the assembly line and/or conveyor belt 1. Due to thiseffect, the present invention requires only narrow covers, such as canbe seen in the drawing FIG. 1 at 12. As a result, the useful platformregion of the carrying elements 2 which is available for assembly or fortransport is substantially larger than is the case in the prior artaccording to FIG. 2. This enlarged work region on the platforms makes itpossible for transport and assembly to continue, unimpeded, even in thecurved region of the assembly line and/or conveyor belt according to theinvention, so that the capacity and availability of the carryingelements are markedly increased.

In the drawing FIG. 4, the frame of the carrying element 2 and thecarrying rollers 13, provided below the carrying element 2 and rollingon the ground, can also be seen in the view of a carrying element 2 frombelow. Furthermore, the convex end faces 6 and 7 of the carrying element2 and, overall, the struts and frame parts allowing high load receptioncan be seen.

FIG. 5 illustrates, isolated, one of the intermediate elements 8; thecoupling rod 10, which is not illustrated in FIGS. 4 and 5, on the onehand, is articulated on the carrying element 2 at 14 and, on the otherhand, is secured centrally at the fastening points 15 of theintermediate piece 8 in such a way that an articulated connection of twocarrying elements 2 in each case to an intermediate piece 8 arrangedbetween them becomes possible.

The frame 16 of the carrying elements 2 or of the intermediate elements8 is covered on the top side by the platform 17 which consistspreferably of wood. The undercarriages with the rollers 13 are, ifappropriate, at least partially driven. Both conventional individualdrives, which are arranged, co-moving, on the carrying elements, and theknown friction-wheel drives, which engage on the carrying elements 2 onthe outside and move these via pushing forces, come into consideration.

1. A curved assembly line and/or conveyor belt for the assembly andtransport of motor vehicles or motor vehicle parts in production,comprising: carrying elements which are mounted in an articulated mannerwith respect to one another and engage positively one into the other andwhich have an upper platform and a lower carrying frame and the endfaces of which are convexly and concavely curved in the form of an arcof a circle with approximately identical radii of curvature, so that ineach case a convex and a concave recess of two adjacent carryingelements form, bearing positively one against the other, a continuousconveyor belt transition both in curved sections and on a straight line;ones of said carrying elements being intermediate carrying elements withconcave end faces that are concave on both sides and others of saidcarrying elements being load-receiving carrying elements with convex endfaces that are convex on both sides, wherein said intermediate carryingelements and said load-receiving carrying elements alternate with oneanother in a longitudinal direction of the assembly line and/or conveyorbelt, and said intermediate carrying elements are short intermediateelements between said load-receiving carrying elements.
 2. The curvedassembly line and/or conveyor belt as claimed in claim 1, wherein amultiplicity of said carrying elements are joined together viaconnecting members into a closed or open composite platform structure.3. The curved assembly line and/or conveyor belt as claimed in claim 2,wherein said connecting members of said carrying elements are couplingrods, wherein two adjacent ones of said load-receiving carrying elementsseparated by a common one of said intermediate carrying elements areconnected to one another in an articulated manner by a common one ofsaid coupling rods, wherein two articulation points of each of saidcoupling rods lying on radius center points of said concave and convexend faces.
 4. The curved assembly line and/or conveyor belt as claimedin claim 3, including roller guides or sliding guides on the end face inthose regions of the load-receiving and intermediate carrying elementswhich face one another.
 5. The curved assembly line and/or conveyor beltas claimed in claim 4, including a drive for said assembly line and/orconveyor belt, said drive comprising a plurality of friction-wheelstations distributed along the travel of said load-receiving andintermediate carrying elements.
 6. The curved assembly line and/orconveyor belt as claimed in claim 4, including a drive for the assemblyline and/or conveyor belt, said drive comprising individual drives whichare assigned to at least every nth one of said load-receiving carryingelements and which are arranged, co-moving, on the corresponding one ofsaid load-receiving carrying elements.
 7. The curved assembly lineand/or conveyor belt as claimed in claim 1 including contact lines tosupply energy and/or data supply to the carrying elements.
 8. The curvedassembly line and/or conveyor belt as claimed in claim 1 including asupply of energy and/or data supply, said supply being permanently orinductively in sections.
 9. The curved assembly line and/or conveyorbelt as claimed in claim 1, including guidance of at least every secondload-receiving carrying element via at least one guide rail laid on theground.
 10. The curved assembly line and/or conveyor belt as claimed inclaim 9, wherein said at least one guide rail comprises one chosen froma single guide rail and a pair of guide rails and wherein the distancebetween said pair of guide rails laid with a spacing between them isreduced in the curved region and wherein said single guide rail isdesigned with a small width in the curve.
 11. The curved assembly lineand/or conveyor belt as claimed in claim 9 wherein said load-receivingintermediate carrying elements are guided on an oval path of rotationwith two straight conveying sections and with semicircular curvesconnecting said straight conveying sections on both sides.
 12. Thecurved assembly line and/or conveyor belt as claimed in claim 9, whereinlateral guidance of said load-receiving carrying elements takes place atouter and/or inner carrying rails.
 13. The curved assembly line and/orconveyor belt as claimed in claim 12, wherein said intermediate elementsrotate, unguided.
 14. The curved assembly line and/or conveyor belt asclaimed in claim 1 including active or passive lifting devices that areinstalled in at least individual ones of said load-receiving carryingelements.
 15. The curved assembly line and/or conveyor belt as claimedin claim 19 including vertical arcs that are provided in the at leastone guide rail for changing the level of the plane of rotation, andwherein said load-receiving and intermediate carrying elements areadditionally connected to one another via horizontal joints.
 16. Thecurved assembly line and/or conveyor belt as claimed in claim 1, whereinsaid intermediate carrying elements are configured to be easilyremovable for inspection and/or maintenance purposes.
 17. The curvedassembly line and/or conveyor belt as claimed in claim 1, whereinvertical load transmission takes place via co-moving steel rollers, saidsteel rollers being mounted rotatably about a vertical axis.
 18. Thecurved assembly line and/or conveyor belt as claimed in claim 1, whereintwo adjacent ones of said load-receiving carrying elements separated bya common one of said intermediate carrying elements are connected to oneanother in an articulated manner by a common coupling rod, wherein twoarticulation points of said coupling rod lying on radius center pointsof said concave and convex end faces.
 19. The curved assembly lineand/or conveyor belt as claimed in claim 1, including roller guides orsliding guides on the end face in those regions of the load-receivingand intermediate carrying elements which face one another.
 20. Thecurved assembly line and/or conveyor belt as claimed in claim 1,including a drive for said assembly line and/or conveyor belt, saiddrive comprising a plurality of friction-wheel stations distributedalong the travel of said load-receiving and intermediate carryingelements.
 21. The curved assembly line and/or conveyor belt as claimedin claim 1, including a drive for the assembly line and/or conveyorbelt, said drive comprising individual drives which are assigned to atleast every nth one of said load-receiving carrying elements and whichare arranged, co-moving, on the corresponding one of said load-receivingcarrying elements.